During floods, river invertebrates may be swept downstream in large numbers. This so-called "catastrophic drift" leads to a major redistribution of animals, as well as reduced fitness and increased ...mortality among drifters. We present the first field evidence of the role of sediment movement in triggering catastrophic drift. Experiments indicate that the loss of invertebrates from the bed becomes exponential when shear stress reaches the threshold that entrains bedload. However, we found that low rates of bedload are sufficient to rapidly denude patches of riverbed of their invertebrates and so trigger mass drift. Such low bedload rates occur during small floods. As small floods occur frequently, our results suggest that episodes of catastrophic drift are frequent. This conclusion is counterintuitive, as the persistence of invertebrate communities on riverbeds suggests that such events cannot be truly catastrophic. Moreover, the drift losses that we observed occurred in the absence of significant geomorphic disturbance; this is inconsistent with the notion of catastrophic drift being a response to hydrological disturbance events. We argue that a new definition of catastrophic drift is needed, a definition based not on drift magnitude or the triggering role of sediment movement, but on the population consequences of downstream displacement.
Several studies based on different populations worldwide have described an association between cardiovascular diseases and genetic variations in the apolipoprotein E (A:POE), angiotensinogen (A:GT), ...angiotensin receptor type 1 (A:T1R), and angiotensin-converting enzyme (A:CE) genes. In addition, there is growing evidence of an interaction between hypercholesterolemia and the renin-angiotensin system in the risk for hypertension and atherosclerosis.
To determine whether the DNA polymorphisms in A:POE (epsilon2, epsilon3, and epsilon4 alleles), A:GT (M235T), A:T1R (1166 A:/C:), and ACE (I:/D:) are associated with early onset of myocardial infarction (MI), we genotyped 220 patients and 200 controls <55 years of age. Patients and controls were males from the same homogeneous Caucasian population. Data concerning hypertension, diabetes, and tobacco consumption were recorded. The lipid profiles of patients and controls were also determined.
APOE, ACE, AGT, and AT1R allele and genotype frequencies did not differ between patients and controls. None of these polymorphisms was related to the biochemical values in patients or controls. The frequency of individuals who were both APOE epsilon4 allele carriers and AGT-TT homozygotes was significantly higher in patients than in controls (11% vs 3.5%; P: = 0.0037). In patients, the frequency of epsilon4 carriers was significantly higher (P: <0.00001) in those who were AGT-TT (46%) than those who were AGT-MT/MM (14%). Mean cholesterol was significantly higher in AGT-TT + APOE epsilon34/44 patients than in the TM/MM + epsilon34/44 or TT + epsilon23/33 genotypes (P: = 0. 029).
Our data suggest a synergistic effect between the APOE and AGT polymorphisms and early MI. The increased risk could be mediated in part through higher cholesterol concentrations among individuals who are AGT-TT + APOE epsilon4 allele carriers.
A series of bedload samples and hydraulic measurements were made in the poorly sorted sandy-gravel bed of the Arbúcies River to determine the threshold conditions for initiation of motion. ...Entrainment has been analysed using two different initial-motion methods: the largest-grain method and the reference or fractional transport rate method. Both methods yield different results in terms of the equal mobility hypothesis. The deviation between scaled and non-scaled initial motion relations are clear: (a) the largest-grain critical shear stress varies to the power −0.68 of
D
i
/
D
50, indicating a tendency towards size-selective entrainment; but (b) computation of the critical shear stress based on the reference transport method indicates only a very weak dependence on grain size (power −0.91). The question is whether such divergent results are caused by real differences or methodological problems. On one hand, estimations of
τ
c from bedload maximum particle size are methodologically problematic. The systematic error associated with determining
D
i
makes it an unreliable estimator of dimensionless critical shear stress. Much of the observed variation between
D
i
and
τ may be more shear-stress estimations or bedload sampling effects than a consequence of selective entrainment. Any conclusion following this method cannot be substantiated, at least until more hydraulic and bedload data is available. On the other hand, scaling problems are less important in the reference transport method, because fractional rates incorporate scaling considerations. Results indicate a strong tendency towards equal mobility, a relatively common situation described in many other transport data, although the coefficient still suggests weak particle dependence. Bedload does not become coarser as shear stress increases, but its grain-size distribution remains constant, as expected under prevailing equal mobility conditions.
To examine the association between coronary artery disease and polymorphisms at the angiotensin-converting enzyme (ACE) and angiotensin II type 1 receptor (AT1R) genes.
A total of 181 patients ...younger than 50 years and 240 controls from the same homogeneous Caucasian population (Asturias, Northern Spain) were genotyped (using polymerase chain reaction) for the ACE insertion/deletion (ACE-I/D) and the AT1R A/C transversion (AT1R-A/C) (3-untranslated region) polymorphisms.
The DD-genotype was at a non-significant higher frequency among patients (50%) than in controls (41%). No difference between the two groups was found for the AT1R-genotypes. Distribution of ACE-genotypes according to AT1R-genotypes showed a significant association between ACE-DD and AT1R-CC and early coronary disease. Among the CC patients 58% were DD, compared to 21% among the controls (p = 0.02; OR = 5.32, 95% CI = 1.45, 19.51). We determined the distribution of these genotypes among the hypertensive and non-hypertensive patients. Frequencies of ACE- or AT1R-genotypes did not differ between the two groups. However, we found an interaction between the DD- and CC-genotypes in the group of normotensives. Among the CC patients, 13% of the hypertensives and 75% of the normotensives were DD (p = 0.014).
Our results indicate a synergistic contribution of ACE and AT1R polymorphisms to the risk of coronary artery disease. This gene-gene interaction could have clinical implications. Approximately 2% of individuals in our population are CC + DD, and the genotyping of both polymorphisms could identify those with a high relative risk for coronary artery disease.
A comprehensive hydro-sedimentological dataset for the Isábena catchment, northeastern
(NE) Spain, for the period 2010–2018 is presented to analyse water and
sediment fluxes in a Mediterranean ...mesoscale catchment. The dataset includes
rainfall data from 12 rain gauges distributed within the study area
complemented by meteorological data of 12 official meteo-stations. It
comprises discharge data derived from water stage measurements as well as
suspended sediment concentrations (SSCs) at six gauging stations of the River
Isábena and its sub-catchments. Soil spectroscopic data from 351
suspended sediment samples and 152 soil samples were collected to
characterize sediment source regions and sediment properties via
fingerprinting analyses. The Isábena catchment (445 km2) is located
in the southern central Pyrenees ranging from 450 m to 2720 m a.s.l.;
together with a pronounced topography, this leads to distinct temperature and
precipitation gradients. The River Isábena shows marked discharge
variations and high sediment yields causing severe siltation problems in the
downstream Barasona Reservoir. The main sediment source is badland areas
located on Eocene marls that are well connected to the river network. The
dataset features a comprehensive set of variables in a high spatial and
temporal resolution suitable for the advanced process understanding of water
and sediment fluxes, their origin and connectivity and sediment budgeting and
for the evaluation and further development of hydro-sedimentological models
in Mediterranean mesoscale mountainous catchments. The dataset is available at http://doi.org/10.5880/fidgeo.2018.011.
Stream invertebrate distribution patterns reflect local sedimentary and hydraulic conditions, which in turn are influenced by a range of factors operating at larger scales. We assessed whether ...spatial variation in invertebrate assemblages across a meso-scale catchment is best understood in terms of the characteristics of the study reaches themselves or the characteristics of respective upstream catchment areas. The study river experiences naturally high fine sediment loads as a result of the extraordinary supply of sediment from high erodible marls in its catchment. We hypothesized that between-reach variation in the volume of fine sediment stored within the channel results from a combination of reach and upstream catchment characteristics, and that these characteristics help explain variation in invertebrate assemblages. The storage of fine sediment in study reaches correlated with a number of upstream catchment characteristics, as well as reach-scale hydraulic conditions. Variability in invertebrate assemblages correlated most strongly (62% of variance explained) with the characteristics of the catchment upstream from each reach (area of contribution), with the characteristics of the reaches accounting for only 35% of the variability. The explanatory power of the reach-scale habitat variables was reduced when the effect of upstream catchment conditions was removed. This suggests inbuilt effects of larger scale conditions on reach habitat and invertebrate assemblages. Results lend support to theories of scale hierarchy within river systems and help emphasize the need to target management at upstream catchment areas.
High-density cholesterol (HDL) levels are affected by genetic influences and certain behaviors. Low levels of HDL-C are considered as an independent risk factor for premature coronary heart disease. ...In patients with Tangier disease, characterised by low HDL levels, mutations in the ATP binding cassette transporter have been described. We have analysed three polymorphisms of the ABCA1 gene (-477C/T, R219 K, and I883M) in a cohort of young male survivors of myocardial infarction in order to know their influence in long-term prognosis. In premature heart disease, knowing prognosis factors is specially relevant.
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